seq                   package:base                   R Documentation

_S_e_q_u_e_n_c_e _G_e_n_e_r_a_t_i_o_n

_D_e_s_c_r_i_p_t_i_o_n:

     Generate regular sequences.

_U_s_a_g_e:

     from:to
     seq(from, to)
     seq(from, to, by=)
     seq(from, to, length=)
     seq(along)

_A_r_g_u_m_e_n_t_s:

    from: starting value of sequence.

      to: (maximal) end value of the sequence.

      by: increment of the sequence.

  length: desired length of the sequence.

   along: take the length from the length of this argument.

_D_e_t_a_i_l_s:

     The interpretation of the unnamed arguments of 'seq' is _not_
     standard, and it is recommended to always name the arguments when
     programming.

     The operator ':' and the first 'seq(.)' form generate the sequence
     'from, from+1', ..., 'to'. 'seq' is a generic function.

     The second form generates 'from, from+by', ..., 'to'.

     The third generates a sequence of 'length' equally spaced values
     from 'from' to 'to'.

     The last generates the sequence '1, 2', ..., 'length(along)',
     unless the argument is of length 1 when it is interpreted as a
     'length' argument.

     If 'from' and 'to' are factors of the same length, then 'from :
     to' returns the "cross" of the two.

     Very small sequences (with 'from - to' of the order of 1e-14 times
     the larger of the ends) will return 'from'.

_V_a_l_u_e:

     The result is of 'mode' '"integer"' if 'from' is (numerically
     equal to an) integer and 'by' is not specified.

_R_e_f_e_r_e_n_c_e_s:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

_S_e_e _A_l_s_o:

     'rep', 'sequence', 'row', 'col'.

_E_x_a_m_p_l_e_s:

     1:4
     pi:6 # float
     6:pi # integer

     seq(0,1, length=11)
     str(seq(rnorm(20)))
     seq(1,9, by = 2) # match
     seq(1,9, by = pi)# stay below
     seq(1,6, by = 3)
     seq(1.575, 5.125, by=0.05)
     seq(17) # same as 1:17

     for (x in list(NULL, letters[1:6], list(1,pi)))
       cat("x=",deparse(x),";  seq(along = x):",seq(along = x),"\n")

     f1 <- gl(2,3); f1
     f2 <- gl(3,2); f2
     f1:f2 # a factor, the "cross"  f1 x f2

